On August 17, 1959, around 11:37 p.m., Yellowstone National Park was changed forever when a large quake shook man-made Hebgen Lake.
According to the U.S. Geological Survey, the quake was the strongest (and deadliest) in Montana history. Over 28 people perished. 80 million tons of dirt, rock and trees slid over the Madison River, damming it off, leading to the creation of Quake Lake.
Yellowstone historian Lee H. Whittlesey gives a good summary of the events in the forward to Larry Morris’ book on the 1959 earthquake:
Yellowstone receives hundreds of small earthquakes per year, and interpreters and geyser-gazers today still discuss the great changes that the ’59 quake imprinted onto the park’s geysers and hot springs. Historians and history buffs still examine with interest old photographs of rock slides, cracked roads and submerged houses, and Old Faithful Inn tour guides still orate about the earthquake damage to that famous building.
The 1959 earthquake was a major, historic event in the Greater Yellowstone Ecosystem because in addition to Yellowstone National Park, it affected southern Montana, western Idaho and parts of northwestern Wyoming that were not inside the world’s first national park.
It’s hard to overstate how terrifying the quake was, how much it rattled the people who found themselves in the area that night. A telling description of the quake in Morris’ book comes from S.B. Gilstad, quoted in the Billings Gazette: “The roar sounded like the end of the world.”